The present invention relates to audio and video synchronization, and more particularly, to synchronizing audio and video data signals by selectively adjusting the video data and the audio data utilizing pre-existing fast and slow forward functions.
Multimedia playback systems, such as DVD players, process both audio and video signals from an optical disc to display audio-visual data. When the transmission of these signals is not synchronized, a sync problem occurs, resulting in either the dialogue preceding the action, or the action preceding the dialogue. When the sync error is small, the effect is negligible; when the sync error is large, however, the effect is significant, and may render the optical disc impossible to watch.
An important feature of multimedia playback systems, therefore, is the ability to re-synchronize the audio and video signals once a sync error is detected. A conventional method is to utilize one stream as the control to either skip or pause data of the other stream in order to achieve synchronization. More clearly, if the audio stream is taken as the control stream and the video stream lags the audio stream (i.e. the dialogue precedes the action), several frames of the video stream will be skipped in order to catch up the audio stream. If, on the other hand, the audio stream is taken as the control stream and the audio stream lags the video stream (i.e. the action precedes the dialogue), a frame of the video stream will be paused to allow the audio stream to catch up.
If the sync error is large, many frames will have to be skipped, or a frame will have to be paused for a significant amount of time, which will be noticeable by the user. This situation is less than ideal.